Two-wheel grinding machine



Nov. 15, 1955 Filed Sept. 20, 1951 07 I I W W M 0 /4/ W L [7 P. A.GROBEY TWO-WHEEL GRINDING MACHINE 4 Sheets-Sheet l 1955 P. A. GROBEYTWO-WHEEL GRINDING MACHINE 4 Sheets-Sheet 2 Filed Sept. 20, 1951 NOV.15, 1955 GROBEY 2,723,497

TWO-WHEEL GRINDING MACHINE Filed Sept. 20, 1951 4 Sheets-Sheet 3 1955 P.A. GROBEY TWO-WHEEL GRINDING MACHINE 4 Sheets-Sheet 4 Filed Sept. 20.1951 United States Patent Ofifice 2,723,497 Patented Nov. 15, 1955 12,723,497 TWO-WHEEL GRINDING MACHINE Paul A. Grobey, Springfield, Vt.,assignor to Bryant Chucking Grinder Company, Springfield, Vt., acorporation of Vermont Application September 20, 1951, Serial No.247,427 15 Claims. (Cl. l-5) This invention relates to grinding machineseach provided with two grinding wheels to each of which the work ispresented at difierent times.

One object of the present invention is to provide improved means forrapidly shifting the work from one to the other of the grinding wheels.

More specifically a further object of the invention is to provide meanswhich gives an initial push to the work holder to change from one to theother of its positions, the momentum imparted by the initial push beingsufficient to carry the work holder through to the other positionWithout further expenditure of moving force.

A further object is to provide in a grinding machine provided with aface grinding wheel improved means for truing the grinding face of sucha Wheel and for feeding the wheel relative to the work piece tocompensate for wheel wear and truing.

Further objects and advantages will appear from a description of themachine shown in the accompanying drawings in which Figure l is a topplan view of a grinding machine embodying the invention.

Figure 2 is a detail sectional view on line 2-2 of Figure 1.

Figure 3 is a detail sectional View on line 3-4 of Figure 2.

Figures 4 and 5 are views similar to portions of Figure 1, but showingthe parts in different positions.

Figures 6, 7 and 8 are detail sectional views on lines 66, 7-7, and 8-8respectively, of Figure 1.

Figure 9 is a fragmentary front elevation showing the face grindingwheel slide approaching its retracted position preparatory to thedressing of the face grinding wheel.

Figure 10 is a detail sectional view on line 10-10 of Figure 7.

Figure 11 is a fragmentary top plan view of the facing wheel holderpartly broken away and in section on line 11-11 of Figure 9.

Referring to the drawings, and more particularly to Figure l, themachine comprises a bed 1 on which is mounted a work head 2 for linearmotion, the direction of this motion being up and down as viewed in thisfigure. It may be mounted on suitable Ways shown as bars 3 and 4 whichmay be connected to the head 2 by expansible and contractibledust-excluding covers 5. Also mounted for linear motion and at rightangles to the work head 2 is a tool head 6. This may be similarlymounted on bars, one of which is shown at 7, likewise being protected bydust guards such as 8. The work head 2 has journaled therein a workspindle having at one end a suitable work holder 10. This work holderand spindle may be rotated as by a motor 11 mounted on the work head andconnected as by a belt 12 to a suitable pulley on the work spindle in amanner well known in the art.

The tool head 6, as shown best in Figures 1 and 11, has journaledtherein a pair of grinding wheel spindles 15' and 16. The spindle 15 hasthereon an axial abrasive grinding. wheel 17, which as shown, may be aninternal grinding wheel arranged to grind an internal bore in a workpiece 18 carried by the work holder 10. The spindle 16, as shown best inFigure 11, carries a face grinding abrasive wheel 20 having an annularend face 21 arranged to grind off the end face of the work piece 18. Thegrinding wheels 20 and 17 can be moved into and out of grinding relationto the work head by the linear motion of the tool head 6.

The face grinding wheel 20 with its spindle 16' is mounted not only forlinear motion with the head 6, but also for motion in the same directionas the head 6 and relative thereto for a purpose which will laterappear. To this end, and as shown in Figure 11, the spindle 16 isjournaled on the bearings 25 and 26' in a casing 27 which is slidablymounted as within the longitudinal ball bearings 28' in a portion 29 ofthe wheel head. This portion of the wheel head is provided with a cap30' which bridges across the rear end of the casing 27 and is secured tothe portion 29 as by bolts 30a; This cap 30 is provided axially with aclosure plug 31 internally threaded at 32 for cooperation with anabutment screw 33' threaded therethrcugh and having its inner end 34'arranged to bear" on a bearing cap 35, closing off a recess 36in thecasing head 37 which houses the bearings 26. The casing 27- is pressedrearwardly to hold it against the inner end of the abutment screw 33 asby one or more springs 40 each seated in a socket 41 in the head portion29 and bearing against a pin 42 slidab'le within the recess and bearingagainst a laterally extended portion of the casing head 37.

As shown, the spindle 16 carries the rotor 44 of a motor, the stator 45of which is fixed to or integral with the casing 27. Thus the facegrinding wheel 20 is adjustable axially as by turning, of the abutmentscrew 33 but is normally held back against this screw. The rear end ofthe screw 33 has secured thereto a hand wheel by which it may bemanually turned, and secured to this hand wheel is a ratchet wheel 51.Cooperating with the teeth of this ratchet Wh68l 51 is a ratchet dog 52(see Figures 8 and 9) pivoted to an arm 53 which is pivoted on a boss 54on the head portion 29, a retaining ring 55 serving to hold the arm 53on the boss 54. On the lower end of the arm- 53" there is journaled acam follower roll 56 with which cooperates at certain times a camelement 57 carried by the bed 1. The arm 53 is normally held as by aspring 58 (see Figure 8) in contact with an adjustable stop screw 59carried by a lug 59a extending from the cap 30, and as shown in Figure8, the angular position in which this arm 53 is normally held is suchthat when the wheel head is moved to the right as viewed in Figure 1sufficiently for the follower roll 56 to engage on the cam 57, this camhas the effect of swinging the arm 53 to the left as viewed in Figure 8,causing the ratchet dog 52 engaging in the teeth of the ratchet wheel 51to turn this wheel, and consequently the abutment screw 33, in adirection to advance the face grinding wheel relative to the Wheel headby a predetermined amount. This is for the purpose of advancing the faceof the grinding wheel preparatory to a face truing operation in orderthat the face truing operation will leave the wheel face at apredetermined distance with respect to the wheel head relative to thework so that when the wheel head is again advanced to a predeterminedpoint the face of the Work will be ground off to a predetermined pointrelative to the work holder.

The means for so truing olf the face of the wheel is shown best inFigures 7 and 10. A shaft 69 (see Figures 1 and 8) is journaledlongitudinally in a casing member 61 secured to the top of the wheelhead 6. The forward end of this shaft 60, as best seen in Figure 10,extends through and is secured in a block a. This block 60a has securedto opposite faces thereof a pair of flat springs 62, 63 the oppositeends of which are secured to an arm 64 which carries at its outer end atruing device 65. As shown in Figure 10, this truing device may beadjusted toward the face of the grinding wheel 20 asby turning anadjusting screw 66 and it may be fixed. in

adjusted position as by tightening a set screw 67. The

springs 62 and 63 allow the dressing tool 65 to be adjustedindependently of the screw 66 toward and from the face of the grindingwheel 20, and this adjustment, as shown, may be produced by the turningof a screw 70 having a knurled head 71 provided with indexing markings72 for cooperation with a pointer 73 carried by the block a. This screwis threaded through the block and its inner end bears against one arm ofa bell crank lever 74 journaled at 75 in an extension bracket 76 of thearm 64. The opposite end of the bell crank lever 74 is rounded as at 76aand bears in a recess 77 in the block 60a. It will be evident that byturning the screw 70, the bell crank lever 74 may be rocked, moving thefulcrum 75 and with it the arm 64 substantially axially with respect tothe grinding wheel 20. The truing device 65 may be arranged to extendthrough an arcuate slot 80 in a guard plate 81 partially covering theouter face of the face grinding wheel 20, this guard plate having a cutaway portion at 82 within which the work piece may be extended when thewheel head is moved axially into grinding relation between the facegrinding wheel and the work. 7

The shaft 60 is rocked to bring the truing device across the annular endface of the face grinding wheel 20 at suitable times. It may be actuatedby hand whenever desired by grasping and moving a handle 85 (see Figure7) extending laterally from the arm 64, but it may also be actuatedautomatically by the retraction of the wheel head to a point beyond thatrequired to effect the compensating feed of the wheel 20. For thispurpose the rear end of the shaft 60 has secured thereto one end of anarm 86 (see Figures 1 and 8) to the outer end of which is pivoted a link87. The lower end of the link 87 is pivoted at 88 (see Figure 9) to anarm 89 fulcrumed at 90 on a bracket 91 projecting from the wheel head 6,and having at its rear end portion a cam roller 92 journaled thereon. Inidle position of the truing device, a stop lug 93 on the arm 89 contactsan adjustable abutment screw 94 as shown in Figure 9, but when the wheelhead is retracted sufficiently, the roller 92 rides up an inclined face95 of a cam block 96, which is pro- 4 vided with a foot 97 by which itmay be attached as by bolts 98 to the top face of the bed 1. Thus as thewheel head is retracted sufiiciently, the arm 89 is lifted, which liftsthe rod 87 and rocks the shaft 60, causing the dressing diamond 65 to beswung across the grinding face of the grinding wheel 20, thus causingthis face to be trued. On forward motion of the wheel head thereafter,the truing device is returned to its starting position shown in Figure 7as by a spring 99 (see Figure 8). It will be noted that the cam 57 whichactuates the feed by acting Y on the cam follower roll 56 has completedits action when the cam roll 92 has been moved sufiiciently to start thedressing of the wheel by the cam 95, the roll 56 still being held on thefiat portion of cam 57 as viewed in Figure 8 while the dressing actionis taking place.

The advance and retraction of the wheel head is produced by rotation ofa cam shaft 100 (see Figures 1, 2 and 6), having a cam actuating afollower 101 on a lever 102, the upper end 103 of which is connected toa rod 104 secured to the Wheel head 6. The wheel head may be normallypressed toward retracted position as by suitable springs including, forexample, a spring 105 shown attached at one end to the lever 102 and atits opposite end to the bed 1.

The work piece carried by the work head may be presented alternatelyinto cooperative relation to the grinding wheels 17 and 20 and suchpresentation may be produced automatically by the rotation of the camshaft 100. It will be understood that this cam shaft 100 is rotated oncefor each cycle of the machine, this rotation being effected by powerfrom any suitable source (not shown).

For the purpose of moving the work head from one to the other of itsoperative relations to the two wheels on the wheel head, the work headis provided with a a pair of bearings 140, 141.

rearwardly extending arm portion 110, shown best in Figures 1 and 4. Atthe rear end of this arm there is journaled therein a shaft 111 carryinga crank arm 112 (see also Figure 3). The outer end of this crank arm hasjournaled therein a crank pin 115 upon which is pivoted one end of alink 116. The other end of this link 116 is provided with a ball portion117 mounted in a socket block 118 having externally threaded thereon aninternally threaded sleeve 119. The sleeve 119 is suitably journaled infixed axial relation in the bed 1 and is provided with a spiral gear 120with which meshes a spiral gear 121 carried by a shaft 122 having a handfeed wheel 123 secured to its outer end. This feed wheel 123 may beturned by hand as desired, or it may be arranged to be movedautomatically by any suitable means as through the rocking of an arm 124journaled thereon and having a ratchet feed mechanism engaging in aratchet wheel 125 secured to the shaft 122. Such arrangements of feedmechanism are old and well known, however, and form no part of thepresent invention. It is sufiicient to say that by turning of the crankmember 112 from the position shown in Figure 5 where it is extended inline with the rod 116 to a position 180 therefrom where the crank arm112 overlaps the rearward end of the rod 116, the work head is movedfrom its position where it may be acted upon the face grinding wheel tothe rearward position where it is in operative relation to the grindingwheel 17. When it is in operative relation to the grinding wheel 17,operation of the feed mechanism which turns the shaft 122 acts toproduce the cross feed motion of the work with reference to the grindingwheel 17.

Means are provided by which the work head may be moved automaticallyfrom one to the other of its operating positions and as shown thismovement is accomplished by a cam carried by the cam shaft 100.Referring to Figures 2, 4 and 5, it will be seen that the cam shaft 100carries a cam provided with two outwardly extending lobes 131 and 132.This cam 130 is adapted to coact with a follower 133 on a lever 134fulcrumed at 135 on a bracket 136 carried by the bed 1. The upper end ofthe lever 134 has pivoted thereto as at 138 a rod 139 which is mountedfor axial sliding motion in At its inner end this rod 139 carries agrooved track member 142 in which is mounted a follower 143 carried bythe crank pin 115. Whenever in the rotation of the cam shaft 100 one ofthe lobes 131 and 132 presses the lower end of the lever 134 inwardly,the upper end of this lever is pulled in the opposite direction and thetrack member 142 is pulled to the left as shown in Figure 4. This actsto turn the crank arm 112 from either of its positions shown in Figures1 and 5 toward the position shown in Figure 4, this giving the work headan impulse tending to move it out of whichever position it happens to bein toward the other position. Figure 3 shows one of these positions infull lines and the other position in dotted lines, these positions beingspaced by substantially double the effective length of the crank arm. Asthe lobes 131 and 132 are quite narrow, this impulse, which is effectiveonly during the first portion of the first half of each full stroke ofthe work head, tends to start the motion of the work head and throughits momentum its motion is continued through the dead center positionwith relation to the rod 139, and until the work head has completed itsfull stroke. A spring connected at one end to the lever 134 and at itsother end to a fixed anchorage 151 on the bed tends to aid in returningthe guide block 142 to its right hand position and completing the motionof the work head from one to the other of its positions. As shown bestin Figure 5, the connection from the upper end of the lever 134 to therod 139 is through a block 155 threaded onto the outer end of the rod139 and having sockets for the reception of the inner ends of clevispins 138 carried by the forked extremity 156 of the lever 134. The camshaft 100 may be provided with other cams for controlling otherfunctions and operations in the machine cycle including, for example,side truing of the grinding Wheel 17, but as these do not constituteportions of the present invention they are not shown nor describedherein.

From the foregoing description of certain embodiments of this invention,it should be evident to those skilled in the art that various changesand modifications may be made therein without departing from its spiritor scope.

I claim:

1. In combination, a bed, a work head, means supporting said work headfor motion on said bed in one linear direction, a pair of grindingwheels mounted on said bed and spaced in the direction of motion or"said work head, a feed member, a shaft journaled in said head, a crankarm on said shaft of a length substantially one half of said space, alink connecting said crank arm to said feed member, and means forrotating said crank arm by steps each of substantially one half arevolution with said crank arm overlapping said link or in substantialalinement therewith and thereby present work on said work holder inoperative relation to one or the other of said wheels.

2. In combination, a bed, a work holding head, means supporting saidwork head for motion on said bed in one linear direction, a pair ofgrinding wheels mounted on said bed and spaced in the direction ofmotion of said work head, a feed member, a shaft journaled in said head,a crank arm on said shaft of a length substantially one half of saidspace, a link connecting said crank arm to said feed member, means forrotating said crank arm by steps each of substantially one half arevolution with said crank arm overlapping said link or in substantialalinement therewith and thereby present work on said work holder inoperative relation to one or the other of said wheels, and means formoving said feed member in the direction of motion of said work holder.

3. In combination, a bed, a work head, means supporting said work headfor motion on said bed in one linear direction, a shaft journaled insaid head, a crank arm fixed to said shaft, a link having one endpivoted to the outer end of said crank arm and extending in the generaldirection of motion of said head, the opposite end of said link having apivotal mounting on said bed, said crank arm when in either of twoangular positions lying substantially in line with the direction ofmotion of said head defining a position of said head, said positionsbeing spaced apart by substantially twice the length of said crank arm,an element movable transverse to the direction of motion of said headand operatively connected to the pivot that is between said link andcrank arm, and means actuable to move said element to move said pivotout of substantial alinement between said arm and link to start motionof said head from one to the other of said positions and then to releasesaid element for return to initial position, to thus permit the momentumof the parts to carry said pivot through dead center position withrespect. to said element and to continue motion of said head to theother of said positions.

4. In combination, a bed, a work head, means supporting said work headfor motion on said bed in one linear direction, a shaft journaled insaid head, a crank arm fixed to said shaft, a link having one endpivoted to the outer end of said crank arm and extending in the generaldirection of motion of said head, the opposite end of said link having apivotal mounting on said bed, said crank arm when in either of twoangular positions lying substantially in line with the direction ofmotion of said head defining a position of said head, said positionsbeing spaced apart by substantially twice the length of said crank arm,an element movable transverse to the direction of motion of said headand operatively connected to the pivot that is between said link andcrank arm, means actuable to move said element to move said pivot out ofsubstantial alinement between said arm and link to start motion of saidhead from one to the other of said positions and then to release saidelement for return to initial position, to thus permit the momentum ofthe parts to carry said pivot through dead center position with respectto said element and to continue motion of said head to the other of saidpositions, and spring means operatively connected to said head to insurecompletion of its motion to such other position.

5. In combination, a bed, a work head, means supporting said work headfor motion on said bed in one linear direction, a pair of grindingwheels mounted on said bed and spaced in the direction of motion of saidwork head, means actuable to start the motion of said work head from oneto the other of two positions in one of which one of said wheels mayoperate on work carried by said work head and in the other of which theother of said wheels may operate on such work, the momentum of said workhead completing its motion to said other position, one of said grindingwheels being a face grinding wheel, means for truing the face of saidface grinding wheel, and means for adjusting said face grinding wheelaxially relative to the other of said wheels to compensate for wheelwear and truing.

6. In combination, a bed, a work head, means supporting said work headfor rectilinear motion on said bed, a wheel head, means supporting saidwheel head for rectilinear motion on said bed in a direction transverseto the direction of motion of said work head, a pair of grinding wheelscarried by said wheel head spaced apart in the direction of motion ofsaid work head, one of said wheels being a face grinding Wheel, and theother of said wheels being an axial grinding wheel, means supportingsaid face grinding wheel for axial motion relative to said wheel head,means for moving said wheel head to bring saidaxial grinding wheel toand from grinding relation to work carried by said work head when saidwork head is in one portion of its path of motion, and said facegrinding wheel to and from grinding relation to said work when said workhead is in another portion of its path of motion, means operativelyconnected to said work head for moving said work head from one to theother of said path positions when said wheel head is retracted, a facetruing device carried by said wheel head, means operatively connected tosaid face grinding wheel and said bed for advancing said face grindingwheel relative to said Wheel head on retraction of said wheel head to apredetermined position to compensate for wear and wheel truing of saidface grinding wheel, and means operatively connected to said truingdevice and bed for actuating said truing device to true said facegrinding wheel on further retraction of said wheel head on said bed.

7. In combination, a bed, a wheel head mounted on said bed for motionthereon in one linear direction, a casing on said wheel head, a wheelspindle journaled in said casing, means supporting said casing on saidwheel head for linear motion, an abutment carried by said head andpositioned to be engaged by said casing and defining the limit ofbackward position of said casing relative to said head, a wheel truingdevice carried by said head and mounted for motion across the face ofsaid Wheel, a cam on said bed, means operatively connected to said headfor moving said head relative to said bed, means for advancing saidabutment and thus advancing said wheel, means carried by said bed andpositioned to be contacted by said cam and be actuated thereby toactuate said advancing means to advance said abutment, casing and wheelrelative to said head on retraction of said head to a predeterminedposition on said bed, a second cam fixed to said bed, and truingactuating means carried by said head and contacted and actuated by saidsecond cam to true said wheel on retraction. of said head further thanfor actuation of said abutment.

8. In combination, a bed, a work head, means supporting said work headon said bed for motion in one linear direction, a shaft journaled insaid head, a crank arm fixed to said shaft, a link having one endpivoted to the outer end of said crank arm and extending in the generaldirection of motion of said head the opposite end of said link having apivotal mounting on said bed, said crank arm when in either of twoangular positions each lying substantially in line with the direction ofmotion of said head defining a position of said head, said positionsbeing spaced apart by substantially twice the length of said crank arm,an element movably mounted on said bed transverse to the direction ofmotion of said head and operatively connected to the pivot that isbetween said link and crank arm, and means actuable to move said elementto move said pivot out of substantial alinement between said arm andlink to start motion of said head from one to the other of saidpositions and then to release said element for return to initialposition to thereby permit the momentum of the parts to carry said pivotthrough said dead center position with respect to said element and tocontinue motion of said head toward the other of said positions.

9. In combination, a bed, a work head, means supporting said work headon said bed for motion in one linear direction, a shaft journaled insaid head, a crank arm fixed to said shaft, a link having one endpivoted to the outer end of said crank arm and extending in the generaldirection of motion of said head the opposite end of said link having apivotal mounting on said bed, said crank arm when in either of twoangular positions each lying substantially in line with the direction ofmotion of said head defining a position of said head, said positionsbeing spaced apart by substantially twice the length of said crank arm,an element movably mounted on said bed transverse to the direction ofmotion of said head and operatively connected to the pivot that isbetween said link and crank arm, means actuable to move said element tomove said pivot out of substantial alinement between said arm and linkto start motion of said head from one to the other of said positions andthen to release said element for return to initial position to therebypermit the momentum of the parts to carry said pivot through said deadcenter position with respect to said element and to continue motion ofsaid head toward the other of said positions, and spring meansoperatively connected to said head to insure completion of its motion tosuch other position.

10. In combination, a bed, a work head, means supporting said work headfor motion on said bed in one linear direction, a pair of grindingwheels mounted on said bed and spaced in the direction of motion of saidwork head, a

feed member, a shaft journaled in said head, a crank arm on said shaftof a length substantially one half of said space, a link connecting saidcrank arm to said feed member, means for rotating said crank arm bysteps each of substantially one half a revolution with said crank armoverlapping said link or in substantial alinement therewith and therebypresent work on said work holder in operative relation to one or theother of said wheels, said rotating means being movable transverse tosaid direction, and connections from said rotating means to said crankincluding interengaging elements relatively movable in said direction.

11. In combination, a bed, a work head, means supporting said work headfor motion on said bed in one linear direction, a pair of grindingwheels movable on said bed and spaced in the direction of motion of saidwork head, means for moving said work head from one to another of a pairof positions in one of which one of said wheels may operate on the workand in the other of which the other of said wheels may operate on saidwork, one of said grinding wheels being a face grinding wheel, means fortruing the face of said face grinding wheel, and means for adjustingsaid face grinding wheel axially relative to the other of said wheels tocompensate for wheel wear and truing.

12. In combination, a pair of members comprising a bed and a work head,means for supporting said work head for motion on said bed in one lineardirection, a link operatively connected at one end to one of saidmembers, a shaft journaled in the other of said members, a crank carriedby said shaft and connected to the other end of said link, said crankand link substantially overlapping in one position of said head andbeing in substantial alinement in another position of said head, andmeans in operative engagement with the juncture of said crank arm andlink mounted for motion laterally of said linear direction and actuableto move said head from either of its positions toward the otherposition.

13. In combination, a bed, a work head, means supporting said work headfor motion on said bed in one linear direction, a pair of grindingwheels mounted on said bed and spaced in the direction of motion of saidwork head, a shaft journaled in said head, a crank arm on said shaft ofa length half that of said space, a link operatively connecting saidcrank arm to said bed, said crank arm overlapping said link when work onsaid work head is in operative relation to one of said wheels and insubstantial alinement therewith when work on said work head is inoperative relation to the other of said grinding wheels, and meansengageable with the connection between said crank arm and link andmovable transverse to the direction of motion of said work head actuableto start the motion of said work head from one to the other of itspositions, momentum of the parts completing such motion.

14. In combination, a pair of members comprising a bed and a work head,means for supporting said work head for motion on said bed in one lineardirection, a feed element on one of said members, a shaft journaled inthe other of said members, a crank carried by said shaft, a linkconnecting said crank to said feed element, said crank and linksubstantially overlapping in one position of said head and being insubstantial alinement in another position of said head, means inoperative engagement with the juncture of said crank arm and linkmounted for motion laterally of said linear direction and actuable tomove said head from either of its positions toward the other position,and means for actuating said feed member to adjust said work head onsaid bed in either position of said crank arm.

15. In combination, a bed, a work head, means supporting said work headfor motion on said bed in one linear direction, a pair of grindingwheels mounted on said bed and spaced in the direction of motion of saidwork head, a feed member carried by said bed, a shaft journaled in saidhead, a crank arm on said shaft of a length half that of said space, alink connecting said crank arm to said feed members, said crank armoverlapping said link when work on said work head is in operativerelation to one of said wheels and in substantial alinement therewithwhen work on said work head is in operative relation to the other ofsaid grinding wheels, means engageable with the connection between saidcrank arm and link and movable transverse to the direction of motion ofsaid work head actuable to start the motion of said work head from oneto the other of its positions, momentum of the parts completing suchmotion, and means for actuating said feed member to adjust said workhead on said bed in either position of said crank arm.

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